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Mentioning intensity, a problem with additive is mixing range.<br>
<br>
[I'm assuming below that levels are the same apparent intensity for
R, G, & B]<br>
If you want to have a range of colors, all apparently the same
intensity, that means you might start with white where you set RGB
to 33% each. But that means every other mix of colors also has to
add up to exactly 99%. You want pure red, no problem, R to 99%.
But trying to mix some other colors gets tricky.<br>
<br>
I just did a holiday toy with RGB LEDs and due to the nature of the
hardware, I've only got 8 dimming levels for 0-100% This gives
exactly 36 possible colors. Plenty for a holiday toy, not so much
for a stage production.<br>
<br>
Oh, as for COB RGB, there's a problem with that. Most LEDs now are
high blue nitride film type and the phosphor is in the silicone
coating over the LED chip (the yellowish rubber blob). These are
brighter, cheaper, and shorter lived. If you're happy with the pure
color emitting older LED chips with no phosphor, then you could do a
COB but I'm guessing there's currently not a lot of call for it.
People buy what's currently made, so why change?<br>
<br>
I guess you could also do a board with a bazillion small surface
mount LEDs, like a video monitor, stripes of RGB, but I'll bet it
wouldn't be cheap.<br>
<br>
<div class="moz-cite-prefix">On 14-Jan-26 1:39, Riter, Andrew via
Stagecraft wrote:<br>
</div>
<blockquote type="cite"
cite="mid:YT4PR01MB9815C1B5E86203A8296061D2FF8EA@YT4PR01MB9815.CANPRD01.PROD.OUTLOOK.COM">
<pre wrap="" class="moz-quote-pre">Thank you all. Interesting. This could be a good discussion.
I like Jerry's point of white source = all colours / RGB = spiky RBG versions of a colour, so subtractive is better colour. But subtractive is also less intensity in the saturated colours.
The question is more: why are subtractive systems CYM and not RGB?
Andrew M. Riter
Assistant Technical Director, Head Lighting Technician
Chan Centre
Phone 604 822 2372
<a class="moz-txt-link-abbreviated" href="mailto:andrew.riter@ubc.ca">andrew.riter@ubc.ca</a>
</pre>
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